Recommended Water Quality Criteria (USEPA 2002), U.S. Department of Energy's Preliminary Remediation Goals for Ecological Endpoints (USDOE 1997), and Ontario MOEE's Rational For The Development and Application of Generic Soil, Groundwater and Sediment Criteria (MOEE 1996).
For chemicals where chronic, No Adverse Effect Level goals or the equivalent were not available, alternative goals were selected and modified as noted (refer also to Table F-4a). Modification factors in general followed recommendations and methods provided in the USEPA Great Lakes water quality initiative guidance (USEPA 1995). USEPA surface water standards for potential bioaccumulation of chemicals in aquatic organisms and subsequent human consumption of these organisms are presented in Table F-4d (incorporated by reference in Guam EPA and CNMI DEQ regulations). These standards should be applied to surface water data only.
5.3.2 Groundwater Screening Levels for Aquatic Habitat Impacts For the purposes of this document, it is assumed that groundwater could discharge into an estuary environment. As such, goals for aquatic habitat protection are based on the lowest of the goals for marine versus freshwater environments. Target surface water goals and correlative groundwater goals can be adjusted on a site-specific basis in areas where this is not appropriate. Dilution of groundwater upon discharge to surface water was not considered in the selection of groundwater screening levels for aquatic habitat protection. Benthic organisms were assumed to be exposed to the full concentration of chemicals in impacted groundwater prior to mixing of the groundwater with surface water. Potential dilution of groundwater upon discharge to surface water or in groundwater "mixing zones" adjacent to shorelines areas was therefore not appropriate for development of conservative screening levels. Adjustment of the final groundwater screening levels with respect to potential dilution may, however, be appropriate on a site-specific basis (e.g., no significant benthic habitat present, see Volume 1, Section 4.4). The USEPA Ecotox goal for barium (3.9 ug/L) was not considered as a screening level for groundwater due to low confidence in the goal and comparison to typical, natural background concentrations of this metal in groundwater (up to >100 ug/L). Background concentrations of boron, copper, lead, mercury, selenium, thallium and zinc may also be present in excess of the groundwater screening levels presented in Tables F-1a and F-1b. This issue should be evaluated on a site-by-site basis as needed.
5.4 Groundwater Screening Levels for Potential Vapor Intrusion Concerns 5.4.1 Vapor Intrusion Model Parameters Groundwater screening levels intended to address the intrusion of vapors into buildings and subsequent impact on indoor-air quality are summarized in Table E-1a and included in Tables FPacific Basin Edition (Fall 2012, rev April 2013)
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APPENDIX 1